Plasma lineation electrode

Abstract

A plasma spray device is provided. The plasma spray device includes a plasma chamber region for having a plasma formed and a throat region coupled to the plasma chamber region. The throat region has an end surface and an axial bore. The axial bore is formed substantially along a longitudinal axis of the throat region, and has a non-circular cross-sectional shape. The axial bore at the end surface is for ejecting a plasma stream. The axial bore may include a plurality of grooves formed substantially along the longitudinal axis of the throat region. The cross-sectional shape of the axial bore may alternatively be defined by a plurality of overlapping substantially circular lobes. The plasma stream has a flow that is lineated before the plasma stream is ejected from the axial bore. The plasma stream has an overall particle pattern angle of less than about 50° after the plasma stream exits the axial bore.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0001] Not Applicable. FIELD OF THE INVENTION [0002] The present invention generally relates to plasma spraying and, in particular, relates to plasma spray methods and apparatus for improved plasma spraying of coating material. BACKGROUND OF THE INVENTION [0003] Plasma spraying is a process in which a coating material is sprayed by a plasma spray device onto a target surface to provide a desired coating. In a conventional plasma spray device, the induced swirling of gas around the cathode centrifugally ejects any injected coating material away from the plasma stream after it exits the anode, reducing the amount of coating material applied to the target surface. In some plasma spray devices, the plasma stream exiting the anode may have an overall particle pattern angle of greater than 90°. The resulting depositional efficiency of the spraying process may be as low as 25% in such an arrangement. Such a low depositional ef...

AI Technical Summary

Benefits of technology

"The present invention is about a plasma spray device with an anode that has a non-circular cross-sectional shape for better lining of the plasma stream flow. This results in higher efficiency and lower processing times. The non-circular shape also reduces wear and tear on the anode, leading to a longer lifespan. The device includes a throat region with an axial bore that has grooves or cross-sectional shapes for better lining of the plasma stream flow. The axial bore is for ejecting the plasma stream. The technical effects of the invention are improved efficiency, lower processing times, reduced wear and tear, and better lining of the plasma stream flow."

Problems solved by technology

The lineation of the flow of the plasma stream reduces the angle of the overall particle pattern of the plasma stream after it exits the anode, resulting in a plasma spray device with a higher depositional efficiency and lower processing times. The turbulence of the plasma stream caused by the transition from a cyclonic flow to a lineated flow reduces the wear on the anode caused by the high energy DC arc used to form the plasma, resulting in a longer consumable life for the anode.

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